diff --git a/src/include/espi.h b/src/include/espi.h
new file mode 100644
index 0000000..b1a51d9
--- /dev/null
+++ b/src/include/espi.h
@@ -0,0 +1,192 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* This file is part of the coreboot project. */
+
+#ifndef __ESPI_H__
+#define __ESPI_H__
+
+/* ESPI Slave Registers (Document # 327432-004 Revision 1.0 Chapter 7) */
+
+#define ESPI_SLAVE_DEVICE_ID				0x04
+#define  ESPI_SLAVE_VERSION_ID_SHIFT			0
+#define  ESPI_SLAVE_VERSION_ID_MASK			0xf
+
+#define ESPI_SLAVE_GENERAL_CFG				0x08
+#define  ESPI_SLAVE_CRC_ENABLE				(1 << 31)
+#define  ESPI_SLAVE_CRC_DISABLE				(0 << 31)
+#define  ESPI_SLAVE_RESP_MOD_ENABLE			(1 << 30)
+#define  ESPI_SLAVE_RESP_MOD_DISABLE			(0 << 30)
+#define  ESPI_SLAVE_ALERT_MODE_PIN			(1 << 28)
+#define  ESPI_SLAVE_ALERT_MODE_IO1			(0 << 28)
+#define  ESPI_SLAVE_IO_MODE_SEL_SHIFT			26
+#define  ESPI_SLAVE_IO_MODE_SEL_MASK			(0x3 << ESPI_SLAVE_IO_MODE_SEL_SHIFT)
+#define  ESPI_SLAVE_IO_MODE_SEL_VAL(x)			((x) << ESPI_SLAVE_IO_MODE_SEL_SHIFT)
+#define  ESPI_SLAVE_IO_MODE_SEL_SINGLE			ESPI_SLAVE_IO_MODE_SEL_VAL(0)
+#define  ESPI_SLAVE_IO_MODE_SEL_DUAL			ESPI_SLAVE_IO_MODE_SEL_VAL(1)
+#define  ESPI_SLAVE_IO_MODE_SEL_QUAD			ESPI_SLAVE_IO_MODE_SEL_VAL(2)
+#define  ESPI_SLAVE_IO_MODE_SUPP_SHIFT			24
+#define  ESPI_SLAVE_IO_MODE_SUPP_MASK			(0x3 << ESPI_SLAVE_IO_MODE_SUPP_SHIFT)
+#define  ESPI_SLAVE_IO_MODE_SUPP_VAL(x)			((x) << ESPI_SLAVE_IO_MODE_SUPP_SHIFT)
+#define  ESPI_SLAVE_IO_MODE_SUPP_SINGLE_ONLY		ESPI_SLAVE_IO_MODE_SUPP_VAL(0)
+#define  ESPI_SLAVE_IO_MODE_SUPP_SINGLE_DUAL		ESPI_SLAVE_IO_MODE_SUPP_VAL(1)
+#define  ESPI_SLAVE_IO_MODE_SUPP_SINGLE_QUAD		ESPI_SLAVE_IO_MODE_SUPP_VAL(2)
+#define  ESPI_SLAVE_IO_MODE_SUPP_SINGLE_DUAL_QUAD	ESPI_SLAVE_IO_MODE_SUPP_VAL(3)
+#define  ESPI_SLAVE_OPEN_DRAIN_ALERT_SEL		(1 << 23)
+#define  ESPI_SLAVE_PUSH_PULL_ALERT_SEL			(0 << 23)
+#define  ESPI_SLAVE_OP_FREQ_SEL_SHIFT			20
+#define  ESPI_SLAVE_OP_FREQ_SEL_MASK			(0x7 << ESPI_SLAVE_OP_FREQ_SEL_SHIFT)
+#define  ESPI_SLAVE_OP_FREQ_SEL_VAL(x)			((x) << ESPI_SLAVE_OP_FREQ_SEL_SHIFT)
+#define  ESPI_SLAVE_OP_FREQ_SEL_20_MHZ			ESPI_SLAVE_OP_FREQ_SEL_VAL(0)
+#define  ESPI_SLAVE_OP_FREQ_SEL_25_MHZ			ESPI_SLAVE_OP_FREQ_SEL_VAL(1)
+#define  ESPI_SLAVE_OP_FREQ_SEL_33_MHZ			ESPI_SLAVE_OP_FREQ_SEL_VAL(2)
+#define  ESPI_SLAVE_OP_FREQ_SEL_50_MHZ			ESPI_SLAVE_OP_FREQ_SEL_VAL(3)
+#define  ESPI_SLAVE_OP_FREQ_SEL_66_MHZ			ESPI_SLAVE_OP_FREQ_SEL_VAL(4)
+#define  ESPI_SLAVE_OPEN_DRAIN_ALERT_SUPP		(1 << 19)
+#define  ESPI_SLAVE_OP_FREQ_SUPP_SHIFT			16
+#define  ESPI_SLAVE_OP_FREQ_SUPP_MASK			(0x7 << ESPI_SLAVE_OP_FREQ_SUPP_SHIFT)
+#define  ESPI_SLAVE_OP_FREQ_SUPP_VAL(x)			((x) << ESPI_SLAVE_OP_FREQ_SUPP_SHIFT)
+#define  ESPI_SLAVE_OP_FREQ_SUPP_20_MHZ			ESPI_SLAVE_OP_FREQ_SUPP_VAL(0)
+#define  ESPI_SLAVE_OP_FREQ_SUPP_25_MHZ			ESPI_SLAVE_OP_FREQ_SUPP_VAL(1)
+#define  ESPI_SLAVE_OP_FREQ_SUPP_33_MHZ			ESPI_SLAVE_OP_FREQ_SUPP_VAL(2)
+#define  ESPI_SLAVE_OP_FREQ_SUPP_50_MHZ			ESPI_SLAVE_OP_FREQ_SUPP_VAL(3)
+#define  ESPI_SLAVE_OP_FREQ_SUPP_66_MHZ			ESPI_SLAVE_OP_FREQ_SUPP_VAL(4)
+#define  ESPI_SLAVE_MAX_WAIT_SHIFT			12
+#define  ESPI_SLAVE_MAX_WAIT_MASK			(0xf << ESPI_SLAVE_MAX_WAIT_SHIFT)
+#define  ESPI_SLAVE_MAX_WAIT_STATE(x)			\
+				(((x) << ESPI_SLAVE_MAX_WAIT_SHIFT) & ESPI_MAX_WAIT_MASK)
+#define  ESPI_SLAVE_FLASH_CH_SUPP			(1 << 3)
+#define  ESPI_SLAVE_OOB_CH_SUPP				(1 << 2)
+#define  ESPI_SLAVE_VW_CH_SUPP				(1 << 1)
+#define  ESPI_SLAVE_PERIPH_CH_SUPP			(1 << 0)
+
+#define ESPI_SLAVE_PERIPH_CFG				0x10
+#define  ESPI_SLAVE_PERIPH_MAX_READ_SIZE_SHIFT		12
+#define  ESPI_SLAVE_PERIPH_MAX_READ_SIZE_MASK		\
+						(0x7 << ESPI_SLAVE_PERIPH_MAX_READ_SIZE_SHIFT)
+#define  ESPI_SLAVE_PERIPH_MAX_READ_SIZE_VAL(x)		\
+						((x) << ESPI_SLAVE_PERIPH_MAX_READ_SIZE_SHIFT)
+#define  ESPI_SLAVE_PERIPH_MAX_READ_64B			ESPI_SLAVE_PERIPH_MAX_READ_SIZE_VAL(1)
+#define  ESPI_SLAVE_PERIPH_MAX_READ_128B		ESPI_SLAVE_PERIPH_MAX_READ_SIZE_VAL(2)
+#define  ESPI_SLAVE_PERIPH_MAX_READ_256B		ESPI_SLAVE_PERIPH_MAX_READ_SIZE_VAL(3)
+#define  ESPI_SLAVE_PERIPH_MAX_READ_512B		ESPI_SLAVE_PERIPH_MAX_READ_SIZE_VAL(4)
+#define  ESPI_SLAVE_PERIPH_MAX_READ_1024B		ESPI_SLAVE_PERIPH_MAX_READ_SIZE_VAL(5)
+#define  ESPI_SLAVE_PERIPH_MAX_READ_2048B		ESPI_SLAVE_PERIPH_MAX_READ_SIZE_VAL(6)
+#define  ESPI_SLAVE_PERIPH_MAX_READ_4096B		ESPI_SLAVE_PERIPH_MAX_READ_SIZE_VAL(7)
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SEL_SHIFT	8
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SEL_MASK	\
+					(0x7 << ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SEL_SHIFT)
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SEL_VAL(x)	\
+					((x) << ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SEL_SHIFT)
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SEL_64B	\
+						ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SEL_VAL(1)
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SEL_128B	\
+						ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SEL_VAL(2)
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SEL_256B	\
+						ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SEL_VAL(3)
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SUPP_SHIFT	4
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SUPP_MASK	\
+					(0x7 << ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SUPP_SHIFT)
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SUPP_VAL(x)	\
+					((x) << ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SUPP_SHIFT)
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SUPP_64B	\
+						ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SUPP_VAL(1)
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SUPP_128B	\
+						ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SUPP_VAL(2)
+#define  ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SUPP_256B	\
+						ESPI_SLAVE_PERIPH_MAX_PAYLOAD_SIZE_SUPP_VAL(3)
+#define  ESPI_SLAVE_PERIPH_BUS_MASTER_ENABLE		(1 << 2)
+
+#define ESPI_SLAVE_VW_CFG				0x20
+#define  ESPI_SLAVE_VW_COUNT_SEL_SHIFT			16
+#define  ESPI_SLAVE_VW_COUNT_SEL_MASK			(0x3f << ESPI_SLAVE_VW_COUNT_SEL_SHIFT)
+/* 0-based field. Value of 0 indicates 1 virtual wire selected. */
+#define  ESPI_SLAVE_VW_COUNT_SEL_VAL(x)			\
+						((x) << ESPI_SLAVE_VW_COUNT_SEL_SHIFT)
+#define  ESPI_SLAVE_VW_COUNT_SUPP_SHIFT			8
+#define  ESPI_SLAVE_VW_COUNT_SUPP_MASK			\
+						(0x3f << ESPI_SLAVE_VW_COUNT_SUPP_SHIFT)
+
+#define ESPI_SLAVE_OOB_CFG				0x30
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SEL_SHIFT	8
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SEL_MASK	\
+					(0x7 << ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SEL_SHIFT)
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SEL_VAL(x)	\
+					((x) << ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SEL_SHIFT)
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SEL_64B	\
+						ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SEL_VAL(1)
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SEL_128B	\
+						ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SEL_VAL(2)
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SEL_256B	\
+						ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SEL_VAL(3)
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SUPP_SHIFT	4
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SUPP_MASK	\
+					(0x7 << ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SUPP_SHIFT)
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SUPP_VAL(x)	\
+					((x) << ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SUPP_SHIFT)
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SUPP_64B	\
+						ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SUPP_VAL(1)
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SUPP_128B	\
+						ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SUPP_VAL(2)
+#define  ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SUPP_256B	\
+						ESPI_SLAVE_OOB_MAX_PAYLOAD_SIZE_SUPP_VAL(3)
+
+#define ESPI_SLAVE_FLASH_CFG				0x40
+#define  ESPI_SLAVE_FLASH_MAX_READ_SIZE_SHIFT		12
+#define  ESPI_SLAVE_FLASH_MAX_READ_SIZE_MASK		\
+						(0x7 << ESPI_SLAVE_FLASH_MAX_READ_SIZE_SHIFT)
+#define  ESPI_SLAVE_FLASH_MAX_READ_SIZE_VAL(x)		\
+						((x) << ESPI_SLAVE_FLASH_MAX_READ_SIZE_SHIFT)
+#define  ESPI_SLAVE_FLASH_MAX_READ_64B			ESPI_SLAVE_FLASH_MAX_READ_SIZE_VAL(1)
+#define  ESPI_SLAVE_FLASH_MAX_READ_128B			ESPI_SLAVE_FLASH_MAX_READ_SIZE_VAL(2)
+#define  ESPI_SLAVE_FLASH_MAX_READ_256B			ESPI_SLAVE_FLASH_MAX_READ_SIZE_VAL(3)
+#define  ESPI_SLAVE_FLASH_MAX_READ_512B			ESPI_SLAVE_FLASH_MAX_READ_SIZE_VAL(4)
+#define  ESPI_SLAVE_FLASH_MAX_READ_1024B		ESPI_SLAVE_FLASH_MAX_READ_SIZE_VAL(5)
+#define  ESPI_SLAVE_FLASH_MAX_READ_2048B		ESPI_SLAVE_FLASH_MAX_READ_SIZE_VAL(6)
+#define  ESPI_SLAVE_FLASH_MAX_READ_4096B		ESPI_SLAVE_FLASH_MAX_READ_SIZE_VAL(7)
+#define  ESPI_SLAVE_FLASH_SHARING_MODE_MAF		(1 << 11)
+#define  ESPI_SLAVE_FLASH_SHARING_MODE_SAF		(0 << 11)
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SEL_SHIFT	8
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SEL_MASK	\
+					(0x7 << ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SEL_SHIFT)
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SEL_VAL(x)	\
+					((x) << ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SEL_SHIFT)
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SEL_64B	\
+						ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SEL_VAL(1)
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SEL_128B	\
+						ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SEL_VAL(2)
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SEL_256B	\
+						ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SEL_VAL(3)
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SUPP_SHIFT	5
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SUPP_MASK	\
+					(0x7 << ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SUPP_SHIFT)
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SUPP_VAL(x)	\
+					((x) << ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SUPP_SHIFT)
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SUPP_64B	\
+						ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SUPP_VAL(1)
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SUPP_128B	\
+						ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SUPP_VAL(2)
+#define  ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SUPP_256B	\
+						ESPI_SLAVE_FLASH_MAX_PAYLOAD_SIZE_SUPP_VAL(3)
+#define  ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_SHIFT	2
+#define  ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_MASK		\
+					(0x7 << ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_SHIFT)
+#define  ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_VAL(x)	\
+					((x) << ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_SHIFT)
+#define  ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_4K		\
+						ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_VAL(1)
+#define  ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_64K		\
+						ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_VAL(2)
+#define  ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_4K_64K	\
+						ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_VAL(3)
+#define  ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_128K		\
+						ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_VAL(4)
+#define  ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_256K		\
+						ESPI_SLAVE_FLASH_BLOCK_ERASE_SIZE_VAL(5)
+
+/*
+ * All channels -- peripheral, OOB, VW and flash use the same bits for channel ready and channel
+ * enable.
+ */
+#define  ESPI_SLAVE_CHANNEL_READY		(1 << 1)
+#define  ESPI_SLAVE_CHANNEL_ENABLE		(1 << 0)
+
+#endif /* __ESPI_H__ */